Alternator Problems?

Question

The alternator in my GMC Sierra was making a loud whistling whining type noise yesterday so I replaced it earlier today and I thought it was fixed but the new alternator has started to make the same noise. It seems kind of unusual that that 2 alternators could be bad in two days.Is there something else that could be causing this. Both alternators are Delco units and my truck is a 1995 with a 5.7 . Any help would be appreciatted, Thanks, Phil Wolf ps. the noise is not constant, and it seems to disappear when accellerating most of the time

News Group · Accepted Answer

Is it the belt tensioner?

no one · Answer

Have the battery Checked , it may be developing a DEAD CELLThe Whinning is Normal if the Alt is Charging a LOW battery or u draw lots of power out of the electrical system!PW wrote:

PW · Answer

It does not seem to be, but I will check again.Thanks, Phil WolfNews Group wrote:

SnoMan · Answer

Under a heavy load (high charging output) GM altenators can and will "whine" at idle and slightly above idle speeds, (sometimes quite noticably) this is not a defect. If it is a new noise for you then you should look for something in truck that is increasing load on altenator or a possible weak/bad battery too.

SnoMan · Answer

Good point and another possibilty too.

PW · Answer

I checked the idler and the belt tensioner again and they are ok. I guess the next step is to ckeck the battery. Thanks for all the replys.Phil WolfSnoMan wrote:

PW · Answer

Well its not the battery either. Any suggestions on what else to check and how to check it would be appreciatted. I am running out of ideas.Thanks, Phil WolfPW wrote:

Rich256 · Answer

Are you certain the noise is from the Alternator?Use something for a Stethoscope to try to verify where the noise is comingfrom.

Greg Surratt · Answer

I can't speak for the original poster, but the last time I replaced a GM alternator, the first thing my SO asked was "Is it supposed to whine like that?"

So I yanked it off, took it back and got another one that had the same noise. Then I told her that it was a new feature so you would know it was working. Case Closed.

Greg

sf/gf · Answer

Greg:That is too funny!!!   I am going to use that same line on my wife the next time she criticizes one of my repairs.SF

PW · Answer

I purchased an automotive stethoscope and the noise is definately coming from the alternator. It is so loud when I come to a stop people look at me like my truck is going to blow up. I have removed every fuse trying to find a circuit that could be conficting with the alternator. If I can"t find the noiseby tomorrow I will return the alternator for an exchange and see what happens, maybe its a badbearing.Thanks for all the replysPhil Wolfsf/gf wrote:

Alternator Problems?

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